deeringiana) for the Management of Meloidogyne spp.

Transcription

1 Supplement to Journal of Nematology 24(4S): The Society of Nematologists Crop Rotation Studies with Velvetbean (Mucuna deeringiana) for the Management of Meloidogyne spp. R. RODRfGUEz-KABANA, 1 J. PINOCHET, 2 D. G. ROBERTSON, 1 AND L. WELLS 3 Abstract: Results from a greenhouse experiment at Cabrils, Spain, with two velvetbean (Mucur~ deeringiana) accessions (Florida and Mozambique) growing in sterilized sandy loam and inoculated with Meloidogyne arenaria race 2, M. irwognita race 1, and M.javanica revealed that the legume was not a host for these nematodes. In contrast, roots of 'Clemson Spineless' okra (Hibiscus esculentum), 'Summer Crookneck' squash (Cucurbita pepo), and 'Davis' soybean (Glycine max) were galled by all three root-knot nematodes. Greenhouse experiments at Auburn, Alabama, using soils infested with Heterodera glycines (race 14) + M. incognita or with H. glycines + M. arenaria (race 2) showed that, in contrast to Davis soybean, a Mexican and the Florida velvetbean accessions were not hosts for the nematodes. An experiment with 'Florunner' peanut (Arachis hypogaea) and the Florida velvetbean in a field infested with M. arenaria (race 1), near Headland, Alabama, showed that significant juvenile populations of the nematode at peanut harvest time were present only in plots with peanut. A microplot rotation experiment demonstrated that 'Black Beauty' eggplant (Solanum melongena) following the Florida velvetbean had heavier shoots and lower numbers of M. arenaria juveniles in the roots and in the soil than eggplant after Summer Crookneck squash or Davis soybean. Key words: cropping system, Heterodera glycines, Meloidogyne arenaria, Meloidogyne incognita, Meloidogyne javanica, Mucuna deeringiana, nematode, nematode control, pest management, root-knot nematode, rotation, soybean cyst nematode, velvetbean. Currently, nematode control in commercial production of many vegetable crops is based on the use of a few restricted nonfumigant nematicides or on preplant applications of limited number of fumigants (methyl bromide, metham sodium, or compositions containing 1,3-D) (1). These materials may not be available to producers in the future because of environmental concerns. It is therefore important to find alternative methods of control. Crop rotation can be an effective method for the management of nematode problems (6,7,18). There are many examples where crops that are nonhosts of Meloidogyne spp. have been used in rotation with susceptible crops to manage problems caused by these nematodes (18). Corn (Zea mays), cotton (Gossypium hirsutum), sorghum (Sorghum bicolor), and a number of other crops can be used to manage root-knot problems in peanut (Arachis hypogaea) and Received for publication 10 May Professor and Research Associate, Department of Plant Pathology, Auburn University, Alabama Agricultural Experiment Station, Auburn, AL Departamento de Patologia Vegetal, Insdtut de Recerca i Tecnologia Agroaliment~ries (IRTA), Cabrils, Barcelona, Spain. a Assistant Superintendent, Wiregrass Substation, Headland, AL soybean (Glycine max) (7,10,11,16). A number of less common or exotic crops are also promising for the development of new rotation systems to control root-knot nematodes (12,13). Velvetbean (Mucuna deeringiana) is an African legume that has been used in the southern United States as a forage and cover crop. Root exudates of this plant are suppressive to Meloidogyne spp. (19), and there is evidence that velvetbean may be an effective rotation crop for the management of root-knot and other soilborne problems (5,19). This study presents information on host response of velvetbean to three Meloidogyne spp. and on the potential of this crop for use in rotations to manage root-knot nematodes. MATERIALS AND METHODS The response of velvetbean to three Meloidogyne spp. was compared to those of five other plant species in a greenhouse experiment (Experiment 1) at the Institut de Recerca i Tecnologia Agroaliment~tries (IRTA), Cabrils, Barcelona, Spain. Meloidogyne spp. cultures were from single egg masses originally isolated from infested plants in Barcelona province. These were: M. arenaria (race 2) from tomato (Lycopersicon esculentum) in Cabrera de Mar; M. in-

2 ognita (race 1) from kiwi (Actinidia deliciosa) in Tordera; and M.javanica from fig (Ficus carica) in Cabrils. Cultures were maintained on 'Garrigues' almond (Prunus amygdalus). Eggs and juveniles were extracted from roots after maceration in NaOC1 solution (2). An aqueous suspension of the inoculum was prepared to deliver 2,500 juveniles and eggs in 5 ml of suspension. Seeds of velvetbean, 'Clemson Spineless' okra (Hibiscus esculentum), 'Stoneville' cotton (Gossypium hirsutum), 'Davis' soybean (Glycine max), and 'Summer Crookneck' squash (Cucurbita pepo) were planted in pots (5 seeds/pot) containing 500 g of fine (~<1 mm mesh), sterilized loamy sand (ph = 8.3, organic matter content ~< 1.0% [w/w], and cation exchange capacity [C.E.C.] ~< 10 meq/100 g soil). Two types of velvetbeans were evaluated: a Florida accession obtained from a commercial source in Alabama and a Mozambique accession obtained from the Regional Plant Introduction Station (USDA, ARS, SAA; Griffin, GA 30223). Plants were allowed to grow for 2 weeks before inoculation. Inoculum was divided and delivered into each pot through five holes 4 to 5 cm deep placed equidistantly in a circle midway from the pot wall and its center. There were five pots per plant and nematode species in the experiment. Inoculated pots were placed in a greenhouse where the plants were maintained under optimal growing conditions, with temperatures fluctuating between 20 and 27 C. Five weeks after inoculation, the plants were removed from the pots, the roots were carefully washed to remove the sand, the number of nematode galls were counted, and fresh root weights were recorded. Two greenhouse experiments were conducted at the Auburn University campus to compare the response of velvetbean with those of Davis soybean and Summer Crookneck squash in soil infested with the soybean cyst nematode (Heterodera glycines race 14) together with M. incognita (Experiment 2), and in soil infested with H. glycines and M. arenaria race 2 (Experiment Velvetbean Rotation: Rodriguez-K(tbana et al ). The soils were from soybean fields near Elberta, Baldwin County, in southwest Alabama. They were sandy loams with ph = 6.2, organic matter content <1.0% (w/w), and C.E.C. <10 meq/100 g soil. For each experiment, the field soil was mixed 50:50 (v:v) with fine (<1 mm mesh) sand, and the moist (60% field capacity) mixture was then apportioned in 1-kg amounts and placed in one-liter-capacity, 10-cm-d cylindrical PVC pots. Soil in the pots was planted with five seeds per pot; in each experiment there were eight pots per plant species. In Experiment 2 (H. glycines + M. arenaria), two velvetbean accessions were used, the Florida velvetbean used in the IRTA experiment and a Mexican accession from Tabasco provided by Dr. Roberto Garcia (Departamento de Fitopatologia, Escuela de Postgraduados, Montecillos, M6xico). In Experiment 3, only the Florida velvetbean was used. The seeded pots were placed in a greenhouse where the resulting plants were maintained in optimal conditions for growth. After 6 weeks, soil and plants were removed from the pots. A subsample of 100 cm 3 soil was taken from each pot. Plants were washed free of soil, the roots were weighed, and the numbers of galls caused by Meloidogyne spp. and numbers of cysts and mature females of H. glycines were counted. The general degree of galling in the roots was assessed using Zeck's root-knot index on a 0-10 scale, in which 0 represents no galls and 10 maximal galling (20). The roots were incubated in water for 72 hours to extract nematodes according to the "salad bowl" incubation technique (14). Nematodes in soil samples were also extracted using the same technique. The effectiveness of velvetbean as a rotation crop for the management of M. arenaria was studied in a microplot experiment at the Old Agronomy Farm on the Auburn University campus. Microplots (30.5 cm 30.5 cm) were delimited by terra-cotta chimney liners with walls 2.5 cm thick. The liners had been placed into holes dug into the ground so that the top 10 cm of the liners were above the soil fine.

3 664 Supplement to Journal of Nematology, Volume 24, December 1992 The liners were filled with soil infested with M. arenaria (30juveniles/100 cm ~ soil). The soil had the same texture and properties as that used for the Auburn greenhouse experiments. Microplots were planted (five seeds/microplot) with Davis soybean, Summer Crookneck squash, and Florida velvetbean. There were 16 microplots for each plant species: eight were treated at-plant with aldicarb and the other eight were left untreated. Aldicarb was applied at a rate of 9 kg a.i./ha on a broadcast basis. The granules were spread evenly over the surface of the microplot and were then worked into the soil to a depth of 3-5 cm using a trowel. There were six treatments in the experiment arranged in a randomized complete block design. The microplots were watered as needed by means of a drip irrigation system. Weed control was by hand, and each plot was fertilized soon after emergence of plants with 20 g of Osmocote (Grace/Sierra, Milpitas, CA) slow-release fertilizer. The plants were allowed to grow for 3 months when they were cut leaving the roots in the soil. Each microplot was then planted with a single 3-week-old 'Black Beauty' eggplant (Solanum melongena). The eggplants were fertilized as described with Osmocote and grew for 2 months, when an early frost killed them. At this time, four 2.5-cm-diam soil cores were taken from each microplot to a depth of cm using a standard soil probe. The cores were pooled and a 100-cm ~ subsample was used for nematological analysis with the "salad bowl" incubation technique (14). The eggplants were then removed, the soil was washed from the roots, and the fresh weights of roots and shoots were recorded. Galls caused by M. arenaria in the roots were counted, and the root system from each plot was incubated to determine nematode numbers using the salad bowl incubation technique. The effect of velvetbean on populations of M. arenaria (race 1) was studied at the Wiregrass substation, near Headland, Alabama, in a peanut (Arachis hypogaea) field. The field had been in peanut with winter fallow for the preceding 15 years. The soil was a sandy loam with ph = 6.0, organic matter content <1.0% (w/w), and C.E.C. <10 meq/100 g soil. Plots in the experiment were eight rows wide and 6 m long; the row width was 0.9 m. The three treatments were 'Florunner' peanut planted with at-plant application of aldicarb, peanut without aldicarb, and Florida velvetbean planted in rows at 11 kg seeds/ha. Aldicarb was applied in a 20-cm-wide band with the seed furrow in the middle of the band at a rate of 31 g a.i./100 m row; the granules were incorporated 2-3 cm into the soil by the action of spring-activated tines attached to the planting equipment. Cultural practices and control of foliar diseases, insects, and weeds in peanut were according to recommendations for the area (3,4). No pesticides were used in plots with velvetbean. The field was watered as needed using a center pivot irrigation system. There were eight replications (plots) per treatment arranged in a randomized complete block design. Peanut and velvetbean were planted on 9 May 1989, and soil samples for nematode analysis were taken on 29 August just before peanut harvest to coincide with the period of maximal M. arenaria juvenile numbers in soil (15). Soil samples were collected from each plot and consisted of cm-diam cores taken with a standard probe. The cores were taken from the plots at approximately 0.3-cm spacings and from the root zone to a depth of cm. Cores from a plot were pooled and a 100-cm 3 subsample was used to determine nematode numbers as described for the other experiments. All data were subjected to standard procedures for analysis of variance (9,17). Fisher's least significant differences (F.L.S.D.) were calculated when F values were significant and are included in the tables of results. Unless otherwise stated, all differences referred to in the text were significant at P ~< RESULTS AND DISCUSSION Experiment 1: All three Meloidogyne spp. failed to develop significant numbers of

4 Velvetbean Rotation: Rodriguez-Kdbana et al. 665 TABL~ 1. Host response of two velvetbeans and five field crop plant species to Meloidog,yne arenaria (race 2), M. incognita (race 1), and M. javanica in a greenhouse experiment (Experiment 1). M. arenar/arace 2 M. incognitarace 1 M. javanica Fresh root No. galls Fresh root No. galls Fresh root No. galls Crop weight (g) per pot weight (g) per pot weight (g) per pot 'Stoneville' cotton 'Clemson Spineless' okra 'Florunner' peanut 'Davis' soybean 'Summer Crookneck' squash Florida velvetbean Mozambique velvetbean F.L,S.D. (P = 0.05) Data are means of five replications. galls in roots of velvetbean, peanut, and cotton. This contrasted with okra, soybean, and squash, in which significant numbers of galls were detected in the roots (Table 1). For each plant species in the experiment, root development was comparable in pots with different Meloidogyne spp. Experiment 2: No galls from M. incognita were found in roots of the Florida velvetbean and no juveniles of the nematode were extracted from roots of either the Florida or the Mexican accessions (Table 2). Soybean and squash roots were moderately galled (root-knot index values = 5-6) and contained significant juvenile populations of M. incognita. Cysts, mature females, and juveniles of H. glycines were found only in soybean roots. Roots of both types of velvetbean contained only males of H. glycines. Juvenile populations of M. incognita in soil were significant only in soil with squash or soybean, whereas H. glycines juveniles were high in numbers only in soil with soybean. Experiment 3: In contrast with squash and soybean, roots of velvetbean had no galls from M. arenaria, and no juveniles of the nematode were extracted from them (Table 3). Significant numbers of cysts, females, and juveniles of H. glycines were associated only with soybean roots. Numbers of juveniles of M. arenaria were highest in soil with squash and were few or none in soils with soybean or velvetbean. Microplot experiment: Eggplants following velvetbean had heavier shoots than those grown after squash or soybean (Table 4). Application of aldicarb did not increase eggplant shoot weight (Table 4) but had an adverse effect on root weights of eggplants TABLE 2. Development ofmeloidogyne incognita and Heterodera glycines on soybean, squash, and velvetbean planted in a greenhouse in soil infested with the two nematode species (Experiment 2). Nematodes per pot Juveniles in roots Juveniles per 100 cm s soil H, g/yf/~2e$ No. galls Galling cysts and M. H. M. H. Crop per g root index? females incognita glycines incognita glycines 'Davis' soybean 'Summer Crookneck' squash Florida velvetbean ~ 7 7 Mexican velvetbean ~t 13 9 F.L.S.D. (P = 0.05) ? Zeck's (20) galling index: :~ All males.

5 TABLE 3. Development of Meloidogyne arenaria race 2 and Heterodera glycines race 14 in soybean, squash, and Florida velvetbean planted in a greenhouse in soil infested with the two nematode species (Experiment 3). Nematodes per pot Juveniles Juveniles per Fresh in roots 100 cm 3 soil root No. galls H. glycines weight per g Galling cysts and M. H. M. H. Crop (g) root indext females incognita glycines incognita glycines 'Davis' soybean 'Summer Crookneck' squash Florida velvetbean F.L.S.D. (P = 0.05) t Zeck's (20) galling index:

6 Velvetbean Rotation: Rodriguez-Kdbana et al. 667 TABLE 4. Effect of the previous crop on growth of 'Black Beauty' eggplant and development of Meloidogyne arenaria race 2 in a microplot experiment at the Old Agronomy Farm on the Auburn Campus. Nematicide Fresh top Galling Galls per Juveniles per Juveniles per Previous crop treatment? weight (g) index* g of root g of root 100 cm s soil Squash (-) Squash ( + ) t Soybean ( - ) Soybean ( + ) Velvetbean ( - ) Velvetbean ( + ) F.L.S.D. (P = 0.05) "~(-) = without nematicide treatment; (+) = with an at-plant application to eggplant of aldicarb at 9 kg a.i./ha. ~: Zeck's (20) galling index: following squash (data not shown). The lowest number of galls per gram of root was for eggplants following velvetbean. A1- dicarb reduced numbers of galls in eggplants following soybean. The numbers of M. arenaria juveniles per gram of fresh root were lowest in eggplant after velvetbean and highest in eggplant after squash. Aldicarb reduced juvenile populations in eggplant roots following squash. Meloidogyne arenariajuvenile soil populations were lowest in soil from microplots with eggplants after velvetbean with aldicarb and highest in those following squash without aldicarb. Aldicarb reduced juvenile populations in eggplants after squash. Field experiment: Highest numbers of M. arenariajuveniles were found in plots with Florunner peanut and the lowest in those with velvetbean (Table 5). Aldicarb reduced juvenile numbers in peanut plots; TABLE 5. Numbers ofmeloidogyne arenaria race 1 juveniles immediately before harvest from a field experiment with 'Florunner' peanut and Florida velvetbean at the Wiregrass substation, near Headland, in southeast Alabama. Crop Juveniles per 100 cm a soil 'Florunner' peanut 188 'Florunner' peanut with aldicarb? 74 Florida velvetbean 23 F.L.S.D. (P = 0.05) 31 "~ Aldicarb was applied at-plant at 31 g a.i./100 m row in a 20-cm-wide band, with the seed furrow in the middle of the band. however, populations in plots with nematicide were higher than in those with velvetbean. Results of this study show that velvetbean is a poor host for the common Meloidogyne spp. in Alabama. This property was true of the three different types of velvetbean tested in our experiments. Velvetbean can be used in combination with corn or other crops to improve soil fertility and to suppress a number of soilborne pathogens (5). There is evidence that root exudates from this plant may exert a suppressive effect on root-knot nematodes (19). Recently, Kloepper et al. (8) showed that rhizosphere bacteria of velvetbean were markedly different from those of soybean and other crops. It is possible that the peculiar rhizosphere microflora of this legume may exert a suppressive effect on Meloidogyne spp. Our results also indicate that velvetbean may be suppressive to H. glycines, suggesting that the effect of the legume on nematodes may be more generalized. There is need to determine the spectrum of activity of velvetbean on other nematodes. Results from the microplot and field experiments indicate that velvetbean may be an excellent rotation crop for the management of root-knot nematode problems in the production of vegetables and other crops. In these experiments, we did not incorporate velvetbean green matter into the soil. The amount of green manure produced by this legume can be in excess of 10 tons dry matter/ha. Incorporation

7 668 Supplement to Journal of Nematology, Volume 24, December 1992 into the soil of such material could enhance soil fertility and possibly result in significant destruction ot~ Meloidogyne inoculum through stimulaticha of microbial activity. Velvetbean grows quickly when soil temperatures are >20-25 C and is ideally suited for the humid subtropical and tropical regions of the world where root-knot nematode problems are common in crop production. LITERATURE CITED 1. Alabama Cooperative Extension Service Alabama Pesticide Handbook. Circular ANR 500, Auburn University, Auburn, Alabama. 2. Barker, K.R Nematode extraction and bioassay. Pp in K. R. Barker, C. C. Carter, and J. N. Sasser, eds. An advanced treatise on Meloidogyne, vol. 2, methodology. Raleigh: North Carolina State University Graphics. 3. Cope, J. T.,Jr., C. E. Evans, and H. C. Williams Soil test fertilizer recommendations for Alabama soils. Circular 252. Agricultural Experiment Station, Auburn University, Auburn, Alabama. 4. Everest, J. W., A. K. Hagan, and J. C. French Peanut pest management. Circular ANR 300, Alabama Cooperative Extension Service, Auburn University, Auburn, Alabama. 5. Granados Alvarez, N La rotaci6n con leguminosas corot alternativa para reducir el dafio causado por fitopat6genos del suelo y elevar la producci6n del agrosistema maiz en el tr6pico ht~medo. Tesis Maestrla en Ciencias. Colegio de Postgraduados, Montecillos, Mrxico. 6. Heald, C. M Classical nematode management practices. Pp inj. A. Veech and D. W. Dickson, eds. Vistas on nematology. Society of Nematologists. 7. Johnson, A. W Managing nematode populations in crop production. Pp in Nematology in the southern region of the United States. Southern Cooperative Series Bulletin 276. Arkansas Agricultural Experiment Station, Fayetteville. 8. Kloepper, J. W., R. Rodriguez-K~ibana, J. A. Mclnroy, and D.J. Collins Analysis of populations and physiological characterization of microorganisms in rhizospheres of plants with antagonistic properties to phytopathogenic nematodes. Plant and Soil 136: Little, T. M., and F.J. Hills Agricultural experimentation. New York: Wiley. 10. Rodriguez-K~bana, R., and H. Ivey Crop rotation systems for the management of Meloidogyne arenaria in peanuts. Nematr6pica 16: Rodrlguez-K~ibana, R., H. Ivey, and P.A. Backman, Peanut-cotton rotations for the management of Meloidogyne arenaria. Journal of Nematology 19: Rodriguez-K~ibana, R., P. S. King, D. G. Robertson, C. F. Weaver, and E. L. Carden New crops with potential for management of soybean nematodes. Nematr6pica 18: Rodrlguez-Khbana, R., P. S. King, D. G. Robertson, and C. F. Weaver Potential of crops uncommon to Alabama for management of root-knot and soybean cyst nematodes. Supplement to the Journal of Nematology 20: Rodriguez-K~tbana, R., and M. H. Pope A simple incubation method for the extraction of nematodes from soil. Nematr6pica 11 : Rodriguez-K~bana, R., C.F. Weaver, D.G. Robertson, and E. L. Snoddy Population dynamics ofmeloidogyne arenariajuvenilec in a field with Florunner peanut. Nematr6pica 16: Rodriguez-K~tbana, R., and J. R. Touchton Corn and sorghum as rotational crops for management of Meloidogyne arenaria in peanut. Nematr6- pica 14: Steel, R. G. D., and J. H. Torrie Principles and procedures of statistics. New York: McGraw- Hill. 18. Trivedi, P. C., and K. R. Barker Management of nematodes by cultural practices. Nematr6pica 16: Vicente, N. E., and N. Acosta Effects of Mucuna deeringiana on MeMdogyne incognita. Nematr6pica 17: Zeck, W. M A rating scheme for field evaluation of root-knot nematode infestations. Pflanzenschutz-Nachrichten 24: